fusion bolt

since all three of the bolt spells are eligible for autocharging, is there some way to apply this to fusion bolt? like if you wanted to charge an f1 icebolt and an f2 firebolt would you be able to do something like press f1 then hold f2, or just hold both of them? i would hope that even in the most basic case you could auto-charge your first spell and add the second into it manually, but i currently do not have that skill so i am not able to test this out myself but it would be really nice if it worked